1. Field of the Invention
The present invention relates to a drilling tool suitable for increasing the diameter of a well bore.
2. Description of the State of the Art
Various system have been proposed for increasing or enlarging the diameter of a well bore.
For example, U.S. Pat. No. 4,589,504 discloses a well bore enlarger comprising a tubular cylindrical housing provided with three cutting arms, said cutting arms pivoting with respect to the housing between a first position in which the arms are within the tubular housing and a second position in which the arms extends partly outside the tubular housing. The enlarger disclosed in said document is only suitable for one specific enlargement of the well bore and is not provided with a blocking means. When using an enlarger of the type disclosed in said document, it appears that due to vibration, the cutting elements are quickly damaged.
The system for increasing the diameter of a well bore of the invention is a system having a high stability and even allowing to adapt continuously or substantially continuously the diameter of the well bore, without need to replace the enlarging tool.